• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.3
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• pp.453-459
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• 1996

This study was carried out to determine the changes in quality during the drying process and the optimum drying condition for utilizing soybean curd residue. The quality criteria for soybean curd residue were acid value, peroxide value, fatty acid composition and microbial concentration. The acid values of soybean curd residue were 7.5, 4.5 and 5.9 KOH mg/g upon 12 hour drying with open-air sun, ambient-air blast and warm-air blast, respectively. The numbers of total aerobic bacteria and molds increased remarkably during drying with open-air sunlight, ambient-air blast and warm-air blast except for hot air blast. Among different drying methods, the hot air blast drying(1kg of sample) was the most effective methods, which completed in three hours. Also, the drying method demonstrated a typical drying curve ; settling down, constant rate drying and falling rate drying period were shown within one hour, from one and three hours and after three hours, respectively. Moreover, there was significant variation in the constant drying period for the quality of soybean curd residue.

• International Journal of Advanced Culture Technology
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• v.3 no.2
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• pp.138-143
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• 2015

This paper was aimed to study the drying kinetics of coffee and to investigate the thin-layer drying kinetics of coffee by using a convective air dryer. The coffee was dried for the temperatures of 40, 50 and $60^{\circ}C$ with relative humidity in the range of 14-25% the airflow rate fixed at 1 m/s. According to the experiment result, the drying rate curve showed that drying process took place only in the falling rate period. Seven thin layer drying models (Newton, Page, Henderson and Pabis, Logarithmic, Wang and Singh, Two terms, Modified Henderson and Pabis) were fitted to the experimental moisture content data. The Two-trem model was found to be a better model for describing the characteristics of coffee for the temperatures of 40, 50 and $60^{\circ}C$. The effective moisture diffusivity of coffee increased when the drying temperature increased. The value was in the range of $4.5028{\times}10^{-11}$ to $6.4803{\times}10^{-11}m^2/s$.

• Journal of Korean Society of Forest Science
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• v.87 no.4
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• pp.577-583
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• 1998

Chestnut and paulownia boards for the traditional musical instruments were air dried to compare moisture contents(MC), drying rates and drying times between the air drying for 70 days in a yard and the shed drying for 150 days in a closed shed when piled in early June. An average final MC and the drying rate of chestnut boards were 20.6 percent and 0.78%/day for the air drying, and 16.6 percent and 0.44%/day for the shed drying. An average final MC and the drying rate of paulownia boards were 16.7 percent and 1.53%/day for the air drying, and 13.5 percent and 0.77%/day for the shed drying. Drying rates of air-dried boards were nearly twice as high as those of shed-dried boards for both species. Air drying rates of chestnut and paulownia boards were very high and exhibited falling drying rate above the fiber saturation point(30%), and then decreased irregularly. However, shed drying rates of chestnut and paulownia boards were high and exhibited falling drying rate above 55 percent MC for chestnut boards and above 80 percent MC for paulownia boards, and then decreased irregularly.

• Journal of the Korean Wood Science and Technology
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• v.25 no.4
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• pp.99-107
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• 1997

This study was executed to test the possibility of replacement for domestic Japanese larch(Larix leptolepis) for hardwoods and to acquire the information about the effects of drying temperature on internal temperature, moisture content and drying defects. In high-temperature drying, internal temperature increased rapidly to boiling point, immediately after that point the internal temperature rising rate was reduced. In the case of drying at temperature of $125^{\circ}C$, internal temperature could reach at boiling point in a very short time. Moisture content in high-temperature drying showed constant drying rate period and first period of falling rate drying together in 4 hours since experiment begun. There was no strong correlation between initial moisture content and final moisture content. Average drying rate at $115^{\circ}C$, $120^{\circ}C$ and $125^{\circ}C$ was 1.42%/hr, 1.88%/hr and 2.02%/hr, respectively; the case of drying temperature of $125^{\circ}C$ showed most rapid drying rate. Drying rate of $125^{\circ}C$ was so rapid that it showed more severe shrinkage, bow, collapse, end check, and internal check development than in other drying conditions. The result of this study showed the strong possibility of high-temperature drying for Japanese larch, and to dry Japanese larch optimally, dry bulb temperature should not exceed $120^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.1
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• pp.64-69
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• 1992

To examine the effects of blanching treatments on the drying of hot red pepper, the pilot scale hot-air dryer equipped with the weight sensor using strain gauge type load cell and strain amplifier was designed and manufactured. The drying characteristic curves of cut hot red pepper showed a settling down period followed by a constant rate period and falling rate period, but blanched hot red pepper showed only falling rate period. According as the blanching time and temperature rises, the drying rates and the capsanthin contents of hot red pepper fairly increased. Considering the drying rates and the color values of dried hot red pepper, we suggest the desirable blanching condition of hot red pepper should be water blanching at $80^{\circ}C$ for 3 mins.

• Journal of Biosystems Engineering
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• v.11 no.1
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• pp.52-63
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• 1986

This study was performed to find out drying characteristics and develop drying model for the design of an efficient dryer or drying system of red peper. The basic model which describes drying phenomenon of red pepper was firstly established, and drying tests were conducted at 14-different drying conditions. In this test, the effects of drying air temperature and relative humidity on the rate of drying were undertaken. Finally, a new drying model based on these experimental results was developed to describe the drying characteristics of red pepper. The results from this study may be summarized as follows. 1. Drying constant of the basic model established from Lewis' experimental model and diffusion equation was theoretically deduced as a function of moisture content and inner-temperature of red pepper. 2. From the results of drying tests, drying air temperature was found to have the greatest effect on the rate of drying. However, the effect of temperature was small for the condition of high relative humidity, and for low temperature, the effect of relative humidity was found to be large even though the range of relative humidity was low. 3. Modified Henderson equation was found to be better than Chung equation as the EMC model for the estimation of the equilibrium moisture content of red Pepper. 4. Constant-rate drying period did not exist in the red pepper drying test. And falling-rate drying period was divided into three distinct phases. Drying rate was dependent on the moisture content, the inner-temperature of red pepper and the change of physical property due to drying. 5. Drying constant increased with decrease of free moisture content, but it decreased at the end of the drying period. Also, drying constant was dependent on the drying air temperature and relative humidity. 6. The new drying model developed in this study was found to be most suitable in describing the drying characteristics of red pepper. Therefore, it may be concluded that drying time could be accurately estimated by the new drying model.

• Korean Journal of Food Science and Technology
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• v.18 no.1
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• pp.61-65
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• 1986

This study was performed to examine the drying characteristics of apples at various drying conditions. Air velocity has no effect on the drying rate except the constant rate period. In this experiment the diffusion coefficients of moisture in the apple tissue were in the range of $1.1470-2.2148{\times}10cm^2/sec$. As a result of balance of heat and mass transfer during the falling rate period. an empirical equation based on Fick's law was obtained as follows; $log{\Delta}t\;=\;log\;t_o\;-\;D{\frac{{\pi}^2{\theta}}{4d.}}$ This equation can be used to calculate the temperature of apples during the falling rate period, provided the diffusion coefficients of apple are known. The experimental values of the internal moisture distribution during apple dehydration were nearly in accord with the theoretical values.

• Journal of Power System Engineering
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• v.14 no.4
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• pp.23-28
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• 2010

Of the roughly four million known substances, about 60,000 are processed and sold ; many of these must be dried. Many materials are processed in the liquid state - ideal for mixing and reacting - but most products are needed or wanted as dry, or relatively dry, solids. Usually operation is just below atmospheric pressure, as with direct dryers, but some are built for vacuum operation with pressures as low as 26.66kPa abs.. In spite of the global-class aquiculture agriculture and fisheries technology of our country, the processing technologies are lags behind the other nations relatively. These problems are considered to be caused directly by the lack of drying technologies. This paper is concerned to the experimental results of drying heat transfer characteristics for the green energy type vacuum dryer for the high quality agriculture and fisheries production.

• Journal of the Korean Applied Science and Technology
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• v.33 no.1
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• pp.58-66
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• 2016

This study was performed to investigate drying characteristics and quality properties of dried persimmon with vacuum drying process. Drying characteristic curve of the dried persimmon showed that the constant rate drying period and falling rate drying period exist definitely. $_{\circ}Brix$, sugar content and hardness value of the dried persimmon increased as the vacuum pressure and heating temperature increased, but L value of the dried persimmon lower. The results indicated that the optimal conditions were at vacuum pressure of 40~50kPa abs., heating temperature of $30^{\circ}C$ and drying time of 3~4days.

• Journal of the Korean Wood Science and Technology
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• v.22 no.2
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• pp.61-70
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• 1994

This study was executed to find the applicability of press drying of tree disk by investigating the shrinkage and drying defect and to form appropriate model by comparing the actual moisture content(MC) and internal temperature in respect of drying time with calculated values based computer simulation to which was applied finite difference method. In press drying disk, heating period, constant drying rate period maintained plateau temperature at 100$^{\circ}C$ and falling drying rate period were significantly distinguished. Actual MC and internal temperature were analogous to those calculated at comparing points. Heat transfer model formed by Fourier's law using specific heat of moist wood and conduction coefficient considering fractional volume of each element of wood cell wall, bound water, free water and air showed applicability as basic data to developing heat expansion, shrinkage and drying stress during press drying. Also mass transfer model formed by Fick's diffusion law using water vapor diffusion coefficient showed applicability. Longitudinal shrinkage was developed by pressure of hot press and tangential shrinkage was restrained by hygrothermal recovery. The heart check, surface check and ring failure were occurred differently in species, but V-shaped crack didn't develop.